Research Article Open Access Plant Pathology & Microbiology Gogoi et al., J Plant Pathol Microb 2013, 4:4 http://dx.doi.org/10.4172/2157-7471.1000171 Volume 4 • Issue 4 • 1000171 J Plant Pathol Microb ISSN:2157-7471 JPPM, an open access journal Keywords: Sulphur; Fungicides; Nano formulations; Powdery mildew; Okra Introduction Powdery mildew is a serious disease of okra, beans, southern peas, squash, cucumbers, muskmelons, and pumpkins in almost all the areas of the country. he disease is caused by the fungus Erysiphe cichoracearum DC ex Merat [Sphaerotheca fuliginea (Schlecht ex Fr.) Poll.)]. Other species of Erysiphe like E. polygoni causes powdery mildew in beans, southern peas, and English peas and Sphaerotheca macularis afects strawberries. Okra or Bhindi or Lady’s inger (Abelmoschus esculentus Moench) is an important vegetable crop. Most of the okra cultivars are susceptible to powdery mildew disease, and depending upon the age of the plant at the time of infection, yield losses range between 17 and 86.6% [1]. he disease is favored by low temperature (11-28°C) and dry weather conditions and early infection has more efect on the plant growth and yield than late infection [2]. Efective control of the disease is possible with fungicidal applications and the recommended fungicides are benomyl (0.1%), wettable sulfur (0.2, 0.3 and 0.5%) [2,3]. Applications of potassium silicate [K 2 SiO 3 (200 mg/L)] and the alternation of systemic fungicide Bayleton WP 5 [Triadimenol (25 mg/L)] and hiovit 80% WP (sulfur (2.4g/L)) with 12 day interval were also highly protective against powdery mildew [4]. Among these fungicides, elemental sulphur (S°) is universally known as the most efective one for managing powdery mildews and this fungicide has been used as foliar spray @ 2-4 g per litres (2000-3000 ppm). As against achieving efective control of powdery mildew disease by using sulphur fungicides, phytotoxicity may be an adverse efect of this fungicide even at recommended doses or due to over use. Hence, it was advised for restricted use of sulphur fungicides in the fruit plants like apple [5] and apricot, vegetables like spinach, melon and squash. To avoid the risk of phytotoxicity, threat to non-targeted organisms and the environment, an idea was conceived to have better control of powdery mildews using lower or safe doses of fungicides. Recently, nanoformulations (particle size <100 nm) of pesticides have been able to draw much attention due to their higher eicacy even at very low doses, because nanoparticles could be more chemically reactive and bioactive than larger particles [6]. We have developed nano-sulphur having 50-90 nm particle size by liquid synthesis method [7] and also standardized a simple method for estimation of active ingredient of sulphur nanoformulation [8]. Subsequently, sulphur nanoparticles were characterized by using dynamic light scattering (DLS) study, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDAX) [8]. he reasons of choosing sulphur for developing into nanoform are that irstly, micronized elemental sulphur (S°) has been in use as a fungicide since long time more particularly in controlling powdery mildew diseases of crops and secondly, this element is having multipronged applications such as fertilizer, pharmaceutical, anti- microbial agent, insecticide, fungicide, high density charger in lithium ion battery as well as rubber and ibre industries [9-15]. Our sulphur nanoparticles exhibited signiicantly superior fungicidal properties than the conventional sulphur against a food contaminant Aspergillus niger [7]. herefore, further investigation was carried out on the eicacy of newly synthesized nano-sulphur against *Corresponding author: Robin Gogoi, Divisions of Plant Pathology, Indian Agricultural Research Institute, New Delhi 110 012, India, E-mail: r.gogoi@rediffmail.com Received January 31, 2013; Accepted March 21, 2013; Published March 26, 2013 Citation: Gogoi R, Singh PK, Kumar R, Nair KK, Alam I, et al. (2013) Suitability of Nano-sulphur for Biorational Management of Powdery mildew of Okra (Abelmoschus esculentus Moench) caused by Erysiphe cichoracearum. J Plant Pathol Microb 4: 171 doi:10.4172/2157-7471.1000171 Copyright: © 2013 Gogoi R, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract New nano-sulphur synthesized at IARI and three other commercial products namely commercial sulphur (Merck), commercial nano-sulphur (M K Impex, Canada) and Sulphur 80 WP (Corel Insecticide) were evaluated in vitro for fungicidal eficacy at 1000 ppm against Erysiphe cichoracearum of okra. All the sulphur fungicides signiicantly reduced the germination of conidia of E. cichoracearum as compared to control. Least conidial germination was recorded in IARI nano-sulphur (4.56%) followed by Canadian nanosulphur (14.17%), Merck sulphur (15.53%), sulphur 80 WP (15.97%) and control (23.09%). Non-germinated conidia count was also high in case of IARI nano- sulphur followed by Canadian nano-sulphur, Merck sulphur and Sulphur 80WP. Apart from inhibition of conidial germination, cleistothecial appendages were also disrupted in contact with nano-sulphur and the cleistothecia became sterile. The study proved that IARI nano-sulphur is more effective than the commercial formulations and could be applied at lower amount for controlling powdery mildew disease for its better eficacy. Suitability of Nano-sulphur for Biorational Management of Powdery mildew of Okra (Abelmoschus esculentus Moench) caused by Erysiphe cichoracearum Robin Gogoi 1 *, Pradeep Kumar Singh 1 , Rajesh Kumar 2 , Kishore Kumar Nair 2 , Imteyaz Alam 2 , Chitra Srivastava 3 , Saurabh Yadav 3 , Madhuban Gopal 2 , Samrat Roy Choudhury 4 and Arunava Goswami 4 1 Divisions of Plant Pathology, Indian Agricultural Research Institute, New Delhi 110 012, India 2 Divisions of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi 110 012, India 3 Department of Entomology, Indian Agricultural Research Institute, New Delhi 110 012, India 4 Indian Statistical Research Institute, Kolkata-700 108, West Bengal, India